The Acyl-CoA Synthetase Encoded by LACS2 Is Essential for Normal Cuticle Development in Arabidopsis

Abstract

Long-chain acyl-CoA synthetase (LACS) activities are encoded by a family of at least nine genes in Arabidopsis (Arabidopsis thaliana). These enzymes have roles in lipid synthesis, fatty acid catabolism, and the transport of fatty acids between subcellular compartments. Here, we show that the LACS2 gene (At1g49430) is expressed in young, rapidly expanding tissues, and in leaves expression is limited to cells of the adaxial and abaxial epidermal layers, suggesting that the LACS2 enzyme may act in the synthesis of cutin or cuticular waxes. A lacs2 null mutant was isolated by reverse genetics. Leaves of mutant plants supported pollen germination and released chlorophyll faster than wild-type leaves when immersed in 80% ethanol, indicating a defect in the cuticular barrier. The composition of surface waxes extracted from lacs2 leaves was similar to the wild type, and the total wax load was higher than the wild type (111.4 mg/dm 2 versus 76.4 mg/dm 2 , respectively). However, the thickness of the cutin layer on the abaxial surface of lacs2 leaves was only 22.3 6 1.7 nm compared with 33.0 6 2.0 nm for the wild type. In vitro assays showed that 16-hydroxypalmitate was an excellent substrate for recombinant LACS2 enzyme. We conclude that the LACS2 isozyme catalyzes the synthesis of v-hydroxy fatty acyl-CoA intermediates in the pathway to cutin synthesis. The lacs2 phenotype, like the phenotypes of some other cutin mutants, is very pleiotropic, causing reduced leaf size and plant growth, reduced seed production, and lower rates of seedling germination and establishment. The LACS2 gene and the corresponding lacs2 mutant will help in future studies of the cutin synthesis pathway and in understanding the consequences of reduced cutin production on many aspects of plant biology.

Nanoridges that characterize the surface morphology of flowers require the synthesis of cutin polyester

“…In the case of Arabidopsis the P450 CYP86A2 (ATT1) (20), LACS2 (19,24), and a pair of redundant acyltransferases, GPAT4 and GPAT8 (12), control most of the accumulation of the dicarboxylic acids in leaf and stem cutin, including the dominant yet unusual monomer octadecadiene-1,18-dioic acid. In the case of suberin, a suberin-associated acyltransferase, GPAT5, and two suberin-correlated P450s, CYP86A1 and CYP86B1, are required for the synthesis of suberin-like monomers in cutin of transgenic Arabidopsis (12,(43)(44)(45).…”

“…In the last few years, the list of genes of cutin biosynthesis in A. thaliana has grown significantly (12,(18)(19)(20)(21)(22)(23)(24)(25). These genes have been shown to affect monomers of stems, leaves, or seeds, but none has been demonstrated to affect the synthesis of the cutin layer in floral organs on the basis of a chemical analysis of cutin.…”

Identification and mapping of SNPs from ESTs in sunflower

“…The situation is further complicated by the fact that some trait differences could be caused by types of genes that are not anticipated (e.g., mineral ion uptake; Table 2) and some genes have numerous possible phenotypic effects. For instance, locus HT218 encodes a putative acyl-CoA synthetase, which is known to be highly pleiotropic in Arabidopsis, causing reduced leaf size and plant growth, reduced seed production, and flower rates of seedling germination and establishment (Schnurr et al 2004). …”

Genome-Wide Identification of Genes Expressed in Arabidopsis Pistils Specifically along the Path of Pollen Tube Growth

“…These include LTPs, of which one proposed function is the transport of cutin monomers to the cell surface (Kader, 1996), and two genes previously implicated in the biosynthesis of cutin in epidermal cells of Arabidopsis: the At1g49430 gene, whose product, LACS2, exhibits long-chain acyl-CoA synthetase activity (Schnurr et al, 2004), and At4g00360 (CYP86A2), which shares 87% amino acid sequence similarity with the fatty acid v-hydroxylase LACERTA (LCR; CYP86A8; Wellesen et al, 2001).…”